Thrond

To add, I'm also curious if the show has even certified if Cadance's backstory is canon - the G.M Berrow books (where the backstory hails from initially) seem to be non-canonical, but it at least fills the giant void that the show has all but forgotten about.

I’m going with it until I hear otherwise and would be sad to see it retconned. 

At least one of the benefits of having G.M Berrow on the writing team (regardless of the... er, inconsistent quality of her episodes thus far) is that there is some microcosmic possibility of it being canonized. With a certain demonic black unicorn tyrant returning next season (judging by leaked vectors), surely Cadance will at least be given some spotlight.

In general though, I feel as if the Crystal Empire and its monarchy are some of the most nefariously neglected elements of the show nowadays. We've had literally only seven or so episodes (depending on how two-parters are counted) where it's even seen, for crying out loud.